How can we help?

“ETO Adjust Factor” Off Target WaterSense Algorithm



  • Avatar
    Ceddy B

    I agree, when September rolls around I have to make manual changes to avoid over watering. I find that in my area daily summer watering simply works best for consistency and avoiding long make up sessions from a 3-4 day a week schedule. But by time I get to September however my Rainmachine does not make sufficient adjustments to water less and I have to scale it back myself. I would love to keep it on a daily schedule during Sept-Oct and have the machine know when enough is enough or to change from daily to every other day on its own.

  • Avatar
    Old Spaghetti

    Yes! There should be an ETo Adjust Factor on the RainMachine unless they have a better solution.  We have been experiencing much colder night temperatures and longer shade time.   The grass roots need to dig in for the winter.  ETo Adjust Factor is merely offset for the ET value used for calculating run times.  Presently the only other RainMachine solution that I can find is to either 

    1. Manually calculate run times reduction and enter zone values individually or,
    2. Change the soil type to one with more field capacity to universally change zone run times.

    (field capacity table at


    FYI:  Rain Birds definition for the ETo Adjust Factor setting:  Fine-Tune Watering

    [If minor adjustments are required to calculated run times, you can increase or decrease run times for ET zones by a selected percentage. These adjustments will apply until you set the value back to 0.

    The Fine Tune % By Zone value can be adjusted from -60% to +60%. For example, if a +50% adjustment is set, then a calculated run time of 10 minutes will become 15 minutes.]

  • Avatar
    Jeff Benjamin

    Agreed - Currently I have three different programs. Spring, Summer and Fall - turning/switching them on/off when the season changes. This fall I am going to play around with 'Crop Coefficient' settings for the 'zones' different for each month. In theory lowering this in Spring and Fall should work.

  • Avatar
    Rolando Soto

    The weather adaptive watering is set for Your program types? That should take care for most of the spring-summer issue (exp. if et0 is 10mm in summer and 5mm in spring Rainmachine will irrigate ~50% of the set value in spring). To see how ET changes over the year You can take a look at the Settings/Wather tab to ET and Seasonal ET adjustments.

    However there are cases where it is necessary to have monthly values for plant coefficient - most notable are the crops which have different water needs on different phases of their growth. You could use that at custom plant settings - I don't recommend using too low values since there is already a reduction of irrigation amount due to low ET's at spring vs summer but You can set 12 values for the 12 months of the Year.

    If You don't know what to set for the rest of the values just use our preset ones:
    You can experiment with the rest of the values too, root depth and crop coefficient lists are existing on the internet so any kind of custom setup can be met.
    There is a good list for plant coefficients here on Table 12:
    And rooth depth list in Table 22 here:

    But be careful and check Your irrigation's a few weeks if You set different values since both values will influence heavily how much irrigation will be done and how much rain can be "stored" in the soil.

    Hope this helps,

  • Avatar
    Old Spaghetti

    For now I am following Jeff’s idea and have installed 6 new programs that reduce the zone watering time in 10% increments (keep it simple).  In the future I may try and implement the solution you propose.  Sure would be nice to have two RainMachines and compare the algorithm results using crop coefficient setting or soil capacity.

  • Avatar
    Old Spaghetti

    Brown,  I am still not happy with program adjustments.  Where and how exactly did you access the Settings/Wather tab / ET and Seasonal ET adjustments?  

  • Avatar

    These seasonal ET adjustments are available on each Zone properties if you set the Vegetation Type to Custom and select "Multiple Monthly Values" instead of "Single Yearly Value".

Please sign in to leave a comment.